IsabelleAikman/Samuel McIlrath, NJ 1755

My Aikman ancestor is Isabelle Aikman b. abt. 1731 m Samuel McIlrath abt. 1755.They had 9 children Mary, Andrew, Agnes (Nancy), Thomas, Jean, Alexander, Elizabeth, Isabel, and Sarah.I have found several references in the New Jersey Archives for William Aikman, John, and Alexander. An article in The Genealogical Magazine of New Jersey, lists Alexander as the youngest son of John.I suspect that Alexander may be the father of Isabelle, but can't find any evidence.If anyone has any suggestions where to look for information on this family I would greatly appreciate any help.Thanks.